1. Field of the Invention
The present invention relates to an evaluation method for forms of rolling bearing parts, such as, inner rings, outer rings or rolling elements.
2. Description of the Prior Art
Form errors or geometric imperfections in a rolling bearing part cause vibration in mechanical apparatus inside which the rolling bearing is incorporated. As a method for managing and controlling the rolling contact surface, which is the raceway surface for the inner ring and the outer ring of the rolling bearing, as well as the rolling contact surface of the rolling elements, which cause vibration, scratches are detected by attendant worker's eye, the surface roughness is measured using a roughness gauge, or the circularity is measured using a circularity measuring gauge. The detected or measured results are compared with associated standard values.
In addition, the order of waviness which causes vibration is determined for the bearing with preload from the geometric relationship (Non-Patent Documents 1 and 2), and therefore, the value of the order of waviness is controlled independently. In this case, the amplitude of the order of waviness can be quantified through harmonic analysis, using a circularity measuring gauge.
Non-Patent Document 1: Tomoya Sakaguchi and Yoshinobu Akamatsu, “Simulation for Ball Bearing Vibration,” NTN Technical Revue, Vol. 69, 2001, pp. 69-75
Non-Patent Document 2: Yoshinobu Akamatsu, “Effects of Rolling Element Material on Vibration of Bearing,” Proceedings of Conference on Tribology by Tribology Society, November 2001, pp. 291 and 292.
In bearings used in a gap state, that is, bearings used under such conditions that a load range and a load-free range exist in the bearings, however, rolling components (rolling elements and raceway rings) which pass through the load range generate vibration in the stationary ring, and therefore, vibration is not caused by waviness of any particular order of waviness, but vibration is caused in the bearing by every order of waviness. Accordingly, in the case where vibration is controlled on the basis of the order of waviness, it is required to devise a technique capable to easily detect whether the waviness of any specific order of waviness has a relatively great amplitude or not.
In this respect, when the relationship between the order of waviness and the amplitude of the above described waviness is expressed on scales with logarithm axes, it becomes linear in a normal work process (Cited Document 2). This is because vibration in the processing machine for the bearing part causes a form error of the bearing, and in general, the higher the degree of vibration is, the smaller the amplitude is. Accordingly, the amplitude or amount of the error of the processed surface in the bearing part decreases in accordance with advance of the order of waviness. However, when the processed surface exhibits abnormal waviness, the amplitude of the order of waviness deviates from the linear relationship.